Methods of remote mining in bedded mineral deposits such as coal seams employ a mining machine that excavates mine openings to some distance from the seam exposure on the surface and means of conveying are required to transport the excavated material to the surface. In most of the present systems, means of conveying consisting of multiple conveyors are advanced into the mine openings from the surface. For example, U.S. Pat. Nos. 5,112,111, 5,232,269 and 5,261,729 to Addington at al. disclose an assembly of conveyors and a mining machine advanced into the seam without interrupting the flow of aggregate material by separate means designed to pull at the forward end and push at the rearward end. Similarly, U.S. Pat. No. 5,609,397 to Marshall at al. discloses an assembly of conveyors interconnected with a mining machine and a driving device located outside the seam and consisting of rack and pinion or, alternately, reciprocating cylinders, linear tracks, linear or rotary drives, chains, cables or other mechanical devices. The U.S. Pat. No. 5,692,807 to Zimmerman discloses a guidance assembly for extending and retracting an assembly of conveyors in and out of the seam. The U.S. Pat. No. 3,497,055 to Oslakovic at al. discloses a multi-unit train of conveyors having a self-propelled unit at each end coupled to intermediate units, each end unit being capable of towing the intermediate units. The U.S. Pat. No. 2,826,402 to Alspaugh at al. discloses a train of wheeled conveyor sections pulled into the mine opening and pushed out of it by a self-propelled mining machine. Buckling of the train is avoided by the grooves made by the mining machine in the floor, said grooves spaced the same distance as the treads of the wheels carrying the conveyor sections.
At present, as the interconnected assembly of the mining machine and a plurality of conveyors is advanced some distance into the seam from a launch vehicle located on the outside, the axial force within the assembly becomes excessive with respect to it's length and the assembly becomes less rigid. As a consequence, it becomes difficult to steer the mining machine located at the front of the assembly and the conveying assembly itself can become unstable, which limits the penetration depth of mining. As well, pulling the conveying assembly at the rearward end when it becomes entrapped by a rock fall may sometimes cause the conveying assembly to brake. It would be therefore desirable to provide means of advancing and withdrawing of the conveying assembly that minimizes the axial force within the conveying assembly.
Where the conveying means consists of a plurality of conveyor units, each of the individual conveyors requires a separate input of electric power which, in turn, requires coupling and uncoupling of electrical cables as the assembly is advanced into or retracted from the mine opening. It would be therefore desirable to provide a power input that does not require electric power at each individual conveyor of the assembly.
If the electric power input is not provided at each individual conveyor, the conveying assembly cannot be extended without interrupting of conveying, as claimed in the U.S. Pat. No. 5,112,111 to Addington at al. It would be therefore desirable to provide means of extending the conveying assembly that minimizes the time required for an extension of the assembly.
Where open conveyors are used, they are prone to damage by falls of rock from unsupported roof. Often, when rock falls occur, mining must be interrupted and the conveying assembly brought to the surface, in order to remove rock fallen onto the assembly and repair damage. It would be therefore desirable to provide means of conveying that is enclosed in a protective enclosure, capable of withstanding at least moderate rock falls.
Electric cables, control cables and hoses for the remote mining machine that lay on the top of the conveying assembly are also prone to damage by rock falls. It would be therefore desirable to provide protective enclosures for cables, hoses and other services provided for the remote mining machine.
The remote mining machine located at the forward end of the conveying assembly may become entrapped by fallen rock and the traction force of the said conveying assembly may not be sufficient to extract the said mining machine. It would be therefore desirable to provide independent means of extracting the mining machine from the seam.